This "super magnets" unfortunately were not so great:
At least the ones I got, never hold 2 kg traction, as listed in the description.
Maybe all 20 together, but that's not the whole point.
For the price paid too cheap to send back.
Hanging now in addition to my magnetic board - that they range from well.
I then another at MTS magnets (also here at Amazon) ordered. These comply with the description / tension perfectly, nothing compared to this one, and only slightly more expensive ...